Research On Preparation And Mechanic Behavior Of Foamed Aluminum With Fine Cell Structure

Foamed aluminum is a kind of new applied material in the 1940’s. Because of its special porous structure, it has some special performance compared with traditional materials such as excellent sound absorption, sound insulation, shock absorption,electromagnetic shielding and absorbing energy and so on, so it is widely used in construction, automobiles, trains, ships, aerospace and protective armor industries and so on.In this paper, foamed aluminum was prepared by powder metallurgy method, and process steps included mixing of powder, cold extrusion, hot extrusion and foaming.By studying the processes, the preparation of foam aluminum could be controlled.Many parameters have great effect on the performance of foamed aluminum. In order to explore the optimum processing conditions of foamed aluminum, the hot extrusion temperature and hot extrusion force were studied. Foamed aluminum was extruded after sintering, the density of foaming samples was more than 98% compared with that of traditional processes. By studying foaming processes, the foaming temperature and time for different porosity were determined.The research results showed that the process route, namely, the mix of powdercold extrusion-sintering-hot extrusion-foaming, can prepare foamed aluminum, void fraction of which was 50%~75%. What’s more, the process route for the preparation of the closed foamed aluminum with special performance was simple, low-pollution and low-consumption. Optimum processing conditions for preparation of foamed aluminum were obtained as follows: foaming time of 10 hours, cold-extrusion force of200 MPa, hot-extrusion force of 300 MPa and hot-extrusion temperature of 400 ℃, the foaming temperature of 680 ℃. By controlling the content of foaming agent and foaming time, different porosity foam aluminum were obtained.Mechanical property of different porosity foamed aluminum was studied. And most of researchers studied the static and dynamic mechanical property at room temperature, but the research on mechanical property of foamed aluminum under high temperature was less. In this paper, the mechanical property of foamed aluminum at high temperature was studied.Quasi static compression experiment of foamed aluminum of different porosity of55%, 65%, 70% was carried out. Results showed that compaction strain and thebiggest energy absorption efficiency increased with the increase of porosity, yield strength, elastic modulus and compaction stress decreased with the increase of porosity.The dynamic impact experiments were carried out for different porosity of foamed aluminum. The experimental data showed platform stress increased with the increases of void fraction. Compared with same porosity materials, platform stress increased during quasi-static compression process. The foamed aluminum of 65% porosity were compressed at the experiment temperature from 25 ℃ to 400 ℃. The results of experiment showed that the modulus of elasticity and platform stress decreased when experimental temperature increased.